THE BERLIN AGING STUDY (BASE) - OVERVIEW AND DESIGN

This article, the introduction to a collection of six related articles , describes the general rationale and design of the Berlin Aging Study (BASE). The distinguishing features of BASE are: (1) a special focus on the very old (70-105 years), (2) broad inter-disciplinarity (medici ne, psychiatry, psychology, sociology and economics), and (3) sample h eterogeneity achieved by local (West Berlin) representativeness. In ad dition to discipline-specific topics, four theoretical orientations gu ide the study: (1) differential ageing, (2) continuity versus disconti nuity of ageing, (3) range and limits of plasticity and reserve capaci ty, and (4) ageing as an inter-disciplinary and systemic phenomenon. T o provide a foundation and framework for the remaining articles, this paper outlines the protocols, designs, and measurement procedures of f ourteen data collection sessions. In addition, information is given on the samples used for empirical analysis. Two samples from the first w ave of the Berlin Aging Study are addressed in this collection of arti cles. The first (N = 360), uses data from the BASE Intake Assessment P rotocol (Session 1). The second (N = 156), employs data from the entir e 14-session full protocol of BASE. Selectivity analyses involving 22 comparison variables are reported in this paper and demonstrate that, with the exception of In-month mortality, these two samples displayed the intended sample heterogeneity. Those results suggest that data fro m BASE hold high generalizability.